Motor evoked potentials of subjects over 70 years of age with and without recurrent falls.

ABSTRACT

Motor evoked potentials (MEPs) of 83 elderly (79+/-4 years) subjects, 43 with recurrent falls and 40 without, and of 31 healthy young (42+/-9 years) subjects were measured from thenar (and hypothenar) and tibialis anterior muscles. Forty-four of the aged subjects without overt neurological diseases were used as controls. Absolute latencies from the cortex to the target muscles as well as the latency differences from the cortex to the level of the fifth lumbar vertebra (LV) were longer in the aged than in the young, but the latency difference from the cortex to the brachial plexus was shorter. The cortical, brachial plexus and lumbar (LV) latencies were all dependent on height as well as age. The latency differences from the cortex to the plexus or LV were not height-dependent but were age-dependent. The thenar MAXMEP/CMAP ratio was significantly higher in hands with thenar atrophy (in 30% of the aged subjects) than without; thenar atrophy thus excludes the use of this parameter in about one-third of the aged subjects. There were no significant differences in the MEP latencies or amplitudes of the recurrent fallers and the non-fallers. Subjects having more frequent falls, however, tended to have lower amplitudes of MEPs in the lower extremities.